1. Field of the Invention
This invention relates to the field of gas conversion and more specifically to the field of synthesis gas production.
2. Background of the Invention
Natural gas, found in deposits in the earth, is an abundant energy resource. For example, natural gas commonly serves as a fuel for heating, cooking, and power generation, among other things. The process of obtaining natural gas from an earth formation typically includes drilling a well into the formation. Wells that provide natural gas are often remote from locations with a demand for the consumption of the natural gas.
Thus, natural gas is conventionally transported large distances from the wellhead to commercial destinations in pipelines. This transportation presents technological challenges due in part to the large volume occupied by a gas. Because the volume of a gas is so much greater than the volume of a liquid containing the same number of gas molecules, the process of transporting natural gas typically includes chilling and/or pressurizing the natural gas in order to liquefy it. However, this contributes to the final cost of the natural gas.
Further, naturally occurring sources of crude oil used for liquid fuels such as gasoline and middle distillates have been decreasing, and supplies are not expected to meet demand in the coming years. Middle distillates typically include heating oil, jet fuel, diesel fuel, and kerosene. Fuels that are liquid under standard atmospheric conditions have the advantage that in addition to their value, they can be transported more easily in a pipeline than natural gas, since they do not require the energy, equipment, and expense required for liquefaction.
Thus, for all of the above-described reasons, there has been interest in developing technologies for converting natural gas to more readily transportable liquid fuels, i.e. to fuels that are liquid at standard temperatures and pressures. One method for converting natural gas to liquid fuels involves two sequential chemical transformations. In the first transformation, natural gas or methane, the major chemical component of natural gas, is reacted with oxygen and/or steam to form synthesis gas (or syngas), which is a combination of carbon monoxide and hydrogen. In the second transformation, which is known as Fischer-Tropsch synthesis, carbon monoxide is reacted with hydrogen to form organic molecules containing mainly carbon and hydrogen. Those organic molecules containing carbon and hydrogen are known as hydrocarbons. In addition, other organic molecules containing oxygen in addition to carbon and hydrogen, which are known as oxygenates, can also be formed during the Fischer-Tropsch synthesis. Hydrocarbons comprising carbons having no ring formation are known as aliphatic hydrocarbons and are particularly desirable as the basis of synthetic diesel fuel.
In the first transformation, the natural gas is typically partially oxidized to form the syngas. Catalytic partial oxidation processes typically include a feedstock that is preheated and mixed with an oxygen source, such as air, oxygen-enriched air, or oxygen, and introduced to a catalyst at elevated temperature and pressure. In order to initiate a catalytic partial oxidation process, the feed may be preheated upstream of the catalyst bed. However, a drawback to this practice is an increased safety hazard as the feed may have an increased chance of auto-ignition. As the pressure increases, the risk of auto-ignition may increase. Such preheating of the feed may also increase the cost of a syngas production unit. A pressure increase may be safely accomplished by reducing the preheat but may negatively affect the performance of the syngas reactor.
Consequently, there is a need for a syngas reactor that has a reduced use of pre-heated feed. In addition, there is a need for a more efficient process of producing syngas. Other needs include reducing the cost and increasing the performance of a syngas reactor.